1. Field of the Invention
The present invention relates to a method of controlling a railroad car in automatic drive on an iron track. The track is divided into transmission zones, essentially independent of the sections of the track (at least when the track is of the "jointless" type).
2. Discussion of Related Art
A device for transmitting information through the rails of a track to a railroad vehicle or car running on the track is described in French Pat. No. 2,431,409. This device is made up of, on the track for each information transmission zone:
an A.C. signal generator alternating at a predetermined frequency which constitutes the carrier frequency for the information transmitted to the cars, this frequency being chosen to be outside of the frequency bands used in track circuits.
a signal modulator,
a command module for controlling the modulator in such a way that the carrier signals are modulated as a function of the information to be transmitted,
at least one isolated conducting loop arranged in the form of a frame between the two lines of rails, near the extreme downward part of the information transmission zone,
an isolation and impedance matching transformer connected such that the primary receives the modulated signals and such that the secondary connects to the terminals of the loop,
two resonating circuits, having resonant frequencies equal to the carrier frequency, connected between the two lines of rails, one being at the extreme downward part and the other being at the extreme upper part of the information transmission zone, and
at an end of each car, reception means having the same frequency as the carrier frequency.